Expander, device for stretching a fabric sheet

ABSTRACT

An expander device for stretching a fabric sheet comprising linkage assemblies which expand and contract in response to the input of a drive means. Fabric gripping elements are connected to the linkage assembly and move linearly as said linkage expands and contracts.

United States Patent. 1191 Vasilantone EXPANDER, DEVICE FOR STRETCHING AFABRIC SHEET [76] Inventor: Michael Vasilantone, 147 E. First Ave.,Roselle, NJ.

[22] Filed: Apr. 24, 1972 [21] Appl. No.1 246,697

152 US. c1. 38/1025, 38/102.91

[51] Int. Cl. D06c 3/08 [58] Field of Search 26/54; 38/1025, 102.6,38/102.91; 160/374, 374.1

[56] References Cited UNITED STATES PATENTS 249.552 11/1881 Seitz 1.160/374 2,752.630 7/1956 Taylor. 26/54 X 3,359,663 12/1967 Black38/1029] 14 1] Feb. 4, 1975 12/1969 Hamu 3,482,343 I 3,601,912 8/197113111163 38/l02.91 FOREIGN PATENTS OR APPLICATIONS. 36,150 7/1886Germany 38/1026 40,666 9/1887 Germany 38/1025 Primary Examiner-Robert R.Mackey Attorney, Agent, or FirmJohn J. Byrne; Edward E. Dyson [57]ABSTRACT An ekpander device for stretching a fabric sheet comprisinglinkage assemblies which expand and contract in response to the input ofa drive means. Fabric gripping elements are connected to the linkageassembly 'and move linearly as said linkage expands and contracts.

6 Claims, 7 Drawing Figures PATENTED FEB 41975 SHEET 10F 3 PATENTEDFEB'M915 3. 863.368 sum 30F 3 EXPANDER, DEVICE FOR STRETCI-IING A FABRICSHEET This invention relates to an expander and, in particular, anexpander for stretching flexible sheets such as textile fabrics in aplurality of different directions simultaneously and equally.

Fabric stretchers per se are not new to the prior art;; however, theprior artdevices are generally unsatisfactory to the extent that theyare unable to maintain uniformity and stability in the fabric during thestretching operation. The result is that the non-uniformly stretchedfabrics may present soft spots". A particular application for anexpander device of the type disclosed herein is in stretching fabricused as stencil screens in screen printing processes. The expanderofthis invention is used to stretch the fabric uniformly after which aframe is placed on the fabric and the fabric is attached thereto by anyconventional means. The expander then releases the material but thatportion attached to the frame remains taut and wrinkled free. Of course,the invention is not limited to the assembly of stencil screen frames. I

Accordingly, it is an objective of this invention to provide an expanderdevice for uniformly stretching a flexible sheet material such as atextile fabric in a plurality of different directions equally andsimultaneously.

It is a further objective of this invention to provide an expanderapparatus which is operable by a single drive means.

It is a further objective of this invention to provide an to thefollowing detailed description when viewed in the light of theaccompanying drawings wherein:

FIG. 1 is a perspective view of the expander of this invention, havingthereon a fabric to be stretched;

FIG. 2 is a plan view of the device of FIG. 1;

FIG. 3 is a view taken on line 33 of FIG. 2;

.FIG. 4 is an exploded view of one of the driving posts of thisinvention;

FIG. 5 is a view taken on line 5-5 of FIG. 3;

FIG. 6 is an exploded view of a fabric gripping element; and

; FIG. 7 is a cross sectional view taken on line 7-7 of FIG. 1.

Referring now to FIG. I, the expander apparatus of this invention isgenerally indicated by the numeral 10 and includes four, equally,radially spaced fabric gripping elements 12 which are mounted on aframework generally indicated by numeral 14 for uniform and simultaneousreciprocatory movement in the direction of the arrows.

The mechanism by which the elements 12 are shifted is more fullyunderstood with reference to FIGS. 2 and 3. The expander is attached toany suitable base 16 by means of mounting pins or any other suitablemounting means 18. The framework 14 consists ofa pair of verticallyspaced plates 20a and 20b. The plates are supported by the mounting pins18 each of which includes an annular flange on which maybe threaded nutor the expander apparatus which is readily adjustable to accommodatefabric panels of different sizes.

It is a further objective of this invention to provide an expanderapparatus which exerts great stretching forces relative to the level offorce input.

More particularly, it is an objective of this invention to provide anexpander device for stretching fabrics comprising a framework, andfabric gripping expander elements mounted on the framework forreciprocatory movement in an outward radial direction relative to thecenter of the framework. Guide means are provided in the framework forguiding the elements in their outward movement. The'means for moving theelements comprises an expandible linkage system connecting each of saidelements, and drive means for expanding the linkage system therebyreciprocating said elements outwardly simultaneously and equally. In apreferred embodiment, the drive means is a threaded, rotatable shafthaving axially spaced, oppositely threaded positions thereon, threadedlyreceived in nuts mounted at spaced points on said linkage means wherebysaid nuts are caused to move toward and away from each other uponrotation of the threaded shaft to contract and expand said linkagemeans. The linkage means in the preferred embodiment comprises twolinkage assemblies each having first and second linkage sections. Eachof the sections comprises four elongated bars of equal length pivotallyconnected to each other and normally assuming a rhombus shape when inplace on saidframework. The second section of each of said assembliesoverlies the first section with its major axis extending transversely tothe major axis of the first section. Connecting means are provided forloosely joining the sections at their points of overlap.

These and other objects of the invention will become more apparent tothose skilled in the art by reference 'like 22 for abutting theundersurface of the plate 20b.

A spacer sleeve 24 is mounted on each of the pins and supports the upperplate 20a in spaced relationship relative'to the lower plate 20b.Each'of the mounting pins is headed at 26 whereby the plates aresecurely held in spaced relationship. The plates are identical inconstruction and, as best seen in FIG. 3, include a plurality ofradially disposed guide slots 28. A pair of linkage assemblies generallyindicated by the numerals 30a and 30b are positioned adjacent plates 20aand 20b. The linkage assemblies are identical, therefore, only one 300will be described in detail, and can best be understood with referenceto FIGS. 2 and 3. The linkage assembly 30a consists of first and secondlinkage sections 32a and 34a. The linkage sections are identical andeach comprises four elongated metal bars or straps 36a and 38a,respectively. The straps of the respective upper and lower linkagesections 30a and 30b are joined together at their outer ends in apivotal connection by means of pins 40 and 42 respectively, to each forma polygon which, as shown in FIG. 3, normally assumes the shape of arhombus when in place on the framework 14. The section 34a underlies thesection 32a and is angularly oriented relative to section 32a such thatthe major axis of section 34a extends transversely of the major axis ofthe section 32a.

v the respective pivotal connection. It can be seen that by means ofthese pivot pins and by means of the aligned slots in plates 20a and 20bof the framework, when the 3 lower linkage assembly is moved radiallyinwardly and outwardly in the slots, the upper linkage assembly movesinan identical manner.

The linkage sections of the respective linkage assemblies a and 30b areconnected together at their points of intersection by means of connectorposts 44 which are best shown in FIGS. 4 and 5. The posts 44 comprise apair of cooperating side members 46 and 48 which when placed togetherdefine upper and lower strap receiving slots 50 and 52, respectively.The width of the slots 50 and 52 is sufficient to'permit the maximumamount of relative pivotal movement between the superposed straps asdefined by the amount of movement permitted by guide slots 28. The postsride in guide slots 29 which are disposed between the guide slots 28.The side members 46 and 48 are held together by means of lockingelements 54 and 56 on the upper and 'lower ends thereof, respectively.Additionally, tension springs 58 and 60 are looped over the upper andlower ends of the members 46 and 48 and further help hold the sectionstogether while permitting expansion,

within the limits permitted by the slots 62 and 64 in the lockingmembers 54 and.56, respectively.

Drive means in the form ofa threaded shaft 66 is rotatably journalled inblocks 68 and 70 disposed between the upper and lower plates 20a and20b. The blocks permit rotational movement of the shaft but preventaxial movement thereof. The shaft has right-and left-hand threadedsections 72 and 74 disposed on either side of the center point of theframework. First and second nuts 76and 78 are fixedly connected to apair of diametrically opposed connector post 44 and threadedly receivethethreaded portions 72 and 74' of the shaft 66. The shaft is providedwith a crank handle 80 to enable manual rotation thereof. It can be seenthat as the shaft is rotated by means of the crank 80, the posts 44 towhich the nuts 76 and 78 are attached will move toward or away from eachother depending on the direction of rotation of the shaft. The movementof the posts is transmitted by means of the straps of the linkagesection to those posts which are not connected to the nut to effect anequal and simultaneous movement of those posts. In other words, thelinkage sections of the linkage assemblies will contract and expandequally within the limits defined by the guide slots in the upper andlower plates 20a and 20bof theframework 14. It is to be understood thatpower means can be utilized to drive the threaded shaft 66 in lieu ofthe crank handle 80.

Gripping elements generally indicated by the nu-' meral 12 are mountedon the outer end of the T-shaped elongated rods 84 which are mounted tothe posts 44 by welding or other suitable means, and are equallyradially spaced from each other. The gripping elements 12 as best seenin FIG. 6 and FIG. 7 each comprise a pair of L-shaped supporting bars 86telescopically mounted on the outer ends of rods 84. The L-shaped bars86 support an elongated channel member 88 on their upper ends andfurther receive a locking channel member 90 with both the members 88 and90 being affixed to the brackets 86 by means of pin fasteners 92 or thelike. The channel member 90 along with the member 88 defines an invertedchannel 94 which receives an elongated locking tube 96 for frictionallyclamping fabric 98 between the outer surface of the locking tube 96, theinner surface of the channel member 90 and the outer surface of themember 88. The

locking tube 96 is preferably coated with a friction surface 100 such asrubber or other elastomeric gripping material.

In operation, it can be seen that a panel to be stretched is placed overthe expander apparatus 10 and the edges thereof are locked in thegripping elements 12 by means of the locking tube 96 and the channelmember 90 as described above. The linkage assemblies 32a and 34a will,of course, be in their collapsed position or in other words, in theposition wherein the pins and posts are at the inner ends of the guideslots 28 and departing from the principle of the present invention ascomprehended within the .scope of the accompanying claims.

I claim:

1. An expander device for stretching fabrics comprising a framework, alinkage system on said framework comprising a pair of parallelogramlinkage sections each having major and minor axes, each parallelogramlinkage section comprising bars connected to each other for relativepivotal movement, said sections being vertically stacked and angularlydisposed relative to each other such that the major axis of one of saidsec tions extends generally transversely to the major axis of the other,said stacked sections defining pointsof overlap, said frameworkincluding a plurality of radially extending guide means slidably mountedtherein, the bars of overlapped linkage sections engaging with saidguide means at said points of overlap, fabric gripper elements mountedfor movement with said guide means and extending outwardly therefrom,drive means operably connected to a single opposed pair of guide meansfor expanding and contracting said linkage system, said guide meansproviding for controlled uniform and simultaneous movement ofsaidgripper elements toward and away from the center of said framework,

2. The expander of claim 1 wherein said drive means comprises a threadedrotatable shaft, and nut means on said opposed pair of guide means forthreadedly receiving said shaft.

3. The expander of claim 1 and including a second pair of linkagesections of identical construction with the first pair of linkagesections and vertically spaced relative to the first pair, and a platedisposed between said vertically stacked pairs of sections, and whereinsaid guidemeans connect said pairs of sections at said 3,863,368 5 6channel therein extending perpendicular to the direcchannel. I tion ofmovement of said gripper elements, and an 6. The expander device ofclaim 1 wherein said elongated locking bar snuggly received in thechannel framework comprises a plate having radially extending of saidmember and clamping the edges of a fabric to slots therein. be stretchedbetween said bar and the walls of said 5 I

1. An expander device for stretching fabrics comprising a framework, alinkage system on said framework comprising a pair of parallelogramlinkage sections each having major and minor axes, each parallelogramlinkage section comprising bars connected to each other for relativepivotal movement, said sections being vertically stacked and angularlydisposed relative to each other such that the major axis of one of saidsections extends generally transversely to the major axis of the other,said stacked sections defining points of over-lap, said frameworkincluding a plurality of radially extending guide means slidably mountedtherein, the bars of overlapped linkage sections engaging with saidguide means at said points of overlap, fabric gripper elements mountedfor movement with said guide means and extending outwardly therefrom,drive means operably connected to a single opposed pair of guide meansfor expanding and contracting said linkage system, said guide meansproviding for controlled uniform and simultaneous movement of saidgripper elements toward and away from the center of said framework. 2.The expander of claim 1 wherein said drive means comprises a threadedrotatable shaft, and nut means on said opposed pair of guide means forthreadedly receiving said shaft.
 3. The expander of claim 1 andincluding a second pair of linkage sections of identical constructionwith the first pair of linkage sections and vertically spaced relativeto the first pair, and a plate disposed between said vertically stackedpairs of sections, and wherein said guide means connect said pairs ofsections at said points of overlap, said plate having radially extendingslots therein for slidably receiving said guide means.
 4. The expanderdevice of claim 3 wherein each of said guide means includes a verticallyextending elongated member having a recess at each end thereof, theportions of said linkage sections of each pair of said points of overlapbeing received in said recesses, and retainer means for maintaining saidportions in said recesses.
 5. The expander of claim I wherein each ofsaid gripper elements includes an elongated member having a channeltherein extending perpendicular to the direction of movement of saidgripper elements, and an elongated locking bar snuggly received in thechannel of said member and clamping the edges of a fabric to bestretched between said bar and the walls of said channel.
 6. Theexpander device of claim 1 wherein said framework comprises a platehaving radially extending slots therein.